Which stat has priority
 

I should have asked the installer but he's now away on holiday :o(

Anyway, just had an Alpha boiler installed (CD32C) and wireless room
stat/programmer/timer thingy. The boiler itself has a thermostat numbered
0-9, there's the room stat, and then all the rads except one have
thermostatic valves. Which thermostat takes priority and what should the one
on the boiler be set at?

TIA,

Puzzled of Cleethorpes

Which stat has priority
 

"John" wrote in message
...
I should have asked the installer but he's now away on holiday :o(

Anyway, just had an Alpha boiler installed (CD32C) and wireless room
stat/programmer/timer thingy. The boiler itself has a thermostat numbered
0-9, there's the room stat, and then all the rads except one have
thermostatic valves. Which thermostat takes priority and what should the
one
on the boiler be set at?


Boiler thermostat sets the temp the water is heated to. Set to achieve about
80°C (prob about 7 on your scale). Room thermostat controls the room temp
(of that room) the boiler cuts out at and as such should have been placed in
a sensible room that is not heated another way. I set mine at 20°C but
something you're comfortable with, the others TRV's on the rads take up the
difference since different parts of the house will cool and heat up at
different rates, so these will all be trial and error to achieve temps
appropriate for the room, ie lounge hot and bedroom cool. So long as you
understand the basis of the setup I have explained the rest is trial and
error for your house. Have your rads been balanced, now is the time to do
that: http://www.diyfaq.org.uk/plumbing/rad-balance.html

--
Mike W

Which stat has priority
 

In an earlier contribution to this discussion,
John wrote:

I should have asked the installer but he's now away on holiday :o(

Anyway, just had an Alpha boiler installed (CD32C) and wireless room
stat/programmer/timer thingy. The boiler itself has a thermostat
numbered 0-9, there's the room stat, and then all the rads except one
have thermostatic valves. Which thermostat takes priority and what
should the one on the boiler be set at?

TIA,

Puzzled of Cleethorpes

None of them in absolute terms - because they are all doing different jobs.

The boiler stat is controlling the temperature of the water leaving the
boiler - typically about 80 degC and, whenever the heating is running, turns
the burner on and off to maintain that.

The room stat attempts to keep the house at the correct temperature
(typically 21 degC) by turning the whole system (boiler plus pump) on and
off as needed.

The TRVs on the radiators attempt to keep each room at the right temperature
by turning individual radiators on and off. These only have any effect when
the system is running so, to that extent, the room stat has priority over
them. Systems should be designed so that the room containing the room stat
(and no TRV on its radiator) heats up slightly more slowly than the other
rooms so as to give the TRVs time to act before the whole lot starts cycling
on the room stat.
--
Cheers,
Roger
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Which stat has priority
 

"visionset" wrote in message
...

"John" wrote in message
...
I should have asked the installer but he's now away on holiday :o(

Anyway, just had an Alpha boiler installed (CD32C) and wireless room
stat/programmer/timer thingy. The boiler itself has a thermostat numbered
0-9, there's the room stat, and then all the rads except one have
thermostatic valves. Which thermostat takes priority and what should the
one
on the boiler be set at?


Boiler thermostat sets the temp the water is heated to. Set to achieve
about 80°C (prob about 7 on your scale). Room thermostat controls the
room temp (of that room) the boiler cuts out at and as such should have
been placed in a sensible room that is not heated another way. I set mine
at 20°C but something you're comfortable with, the others TRV's on the
rads take up the difference since different parts of the house will cool
and heat up at different rates, so these will all be trial and error to
achieve temps appropriate for the room, ie lounge hot and bedroom cool.
So long as you understand the basis of the setup I have explained the rest
is trial and error for your house. Have your rads been balanced, now is
the time to do that: http://www.diyfaq.org.uk/plumbing/rad-balance.html

--

Thanks Mike, a couple of interesting points there. We've had a whole new CH
system fitted (not just a replacement boiler) so yes, he balanced the rads
as part of the job. Because it was done in the summer and we've not needed
the heating on before now, we've only just noticed a problem in that he
mounted the room stat in the lounge, which is the hottest room in the house
because of the TV, the fire, the computer and the three people who usually
sit in it

The stat is wireless so can be easily moved to another room but I remember
reading somewhere that there should always be one rad in the system that
doesn't have a TRV and that the stat is usually in that room, which in our
case, it is - the radiator in the lounge is the one that doesn't have a TRV.
So can the room stat safely be mounted in another room?

John.

Which stat has priority
 

In message , John
writes
I should have asked the installer but he's now away on holiday :o(

Anyway, just had an Alpha boiler installed (CD32C) and wireless room
stat/programmer/timer thingy. The boiler itself has a thermostat numbered
0-9,

That's a temperature control - when the water temperature reaches the
temperature you have set it to, it will turn the gas valve off

there's the room stat,

Which will turn the boiler off when the room temp reaches the set
temperature


and then all the rads except one have
thermostatic valves.

Which will prevent water going through that particular rad when the head
if the TRV reaches the set temp

Which thermostat takes priority and what should the one
on the boiler be set at?

None, they are all doing different things

so, for example, set the boiler ctrl high and the rads will heat up
faster because the water temp is hotter and then either the TRV will cut
the water to the rad or the room stat will cut the boiler

Really your room stat is redundant if you are going to use the TRVs


--
geoff

Which stat has priority
 

"John" wrote in message
...

The stat is wireless so can be easily moved to another room but I remember
reading somewhere that there should always be one rad in the system that
doesn't have a TRV and that the stat is usually in that room,

Actually regs say it must be in that room, but you can of course do what you
like.

which in our case, it is - the radiator in the lounge is the one that
doesn't have a TRV. So can the room stat safely be mounted in another
room?

Yes but of course you can easily have the situation that the TRV and
thermostat will conspire to keep the rest of the house at the temperature
required by that room whilst the room itself is actually stone cold! And
the room without stat or TRV will have no control at all other than the
programmed timings.

--
Mike W

Which stat has priority
 

Really your room stat is redundant if you are going to use the TRVs

Except that this is not permitted without some other form of interlock, as
the boiler will continue to cycle even when all the TRVs are off, which is
wasteful of gas and not permitted by the building regulations.

Christian.

Which stat has priority
 

Christian McArdle wrote:

Really your room stat is redundant if you are going to use the TRVs


Except that this is not permitted without some other form of interlock, as
the boiler will continue to cycle even when all the TRVs are off, which is
wasteful of gas and not permitted by the building regulations.

and in some cases might no do the pump any favours either!

--
Cheers,

John.

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Which stat has priority
 

John wrote:

The stat is wireless so can be easily moved to another room but I remember
reading somewhere that there should always be one rad in the system that
doesn't have a TRV and that the stat is usually in that room, which in our
case, it is - the radiator in the lounge is the one that doesn't have a TRV.
So can the room stat safely be mounted in another room?

You have two problems to solve if you move it (and by the sounds of it
you ought to, because the other heat sources in the lounge could result
in you have a nice warm lounge and a cold house).

1) you need to ensure the TRV in the room you place the stat is not
going to stop the system working properly. This is usually straight
forward if you can remove the TRV head (they have a locking ring that
unscrews from the valve base) leaving the rad uncontrolled and at its
maximum setting.

2) You need some form of control in the lounge. The "best" solution
would be to install a TRV on this rad. However you may find that you can
achieve enough comfort simply relying on the timer/boiler cycling and
setting the rad flow rate manually. Perhaps allowing for adding top up
heat to the room from the fire etc.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Which stat has priority
 

"John Rumm" wrote in message
...
Christian McArdle wrote:

Really your room stat is redundant if you are going to use the TRVs


Except that this is not permitted without some other form of interlock,
as the boiler will continue to cycle even when all the TRVs are off,
which is wasteful of gas and not permitted by the building regulations.

and in some cases might no do the pump any favours either!

Thanks very much to all of you. I'm much happier now that I know what's
going on with my system.

John.